Chapter 31- Deuterostomes

What are the three groups of deuterostomes?

Enchinoderms, hermichordates, chordates 

What environment do hemichordates and echinoderms live?

Marine

How does the coelem form in deuterostomes?

Mesodermal pouches pinch off from gut

Enterocoely

Pouches pinch off embryonic gut

Developmental traits in deuterostomes

Radial cleavage, blastopore becomes anus, coelem develops from mesodermal pockets that bud off from gut

What is the strongest evidence for monophyly of deuterostomes?

DNA sequencing 

What is the cleavage pattern in deuterostomes?

Radial

What molecular evidence do deuterostomes have?

Monophyletic

What are the types of echinoderms?

Sea stars, sea urchins, and sea cucumbers

What are the types of hemichordates?

Acorn worms and pteobranchs 

What are the types of chordates?

Tunicates,lanceletes, vertebrates

Which groups are ambulacrarians?

Echinoderms and hemichordates

What kind of symmetry do echinoderm adults have?

Pentaradial symmetry

What kind of symmetry do hemichordate adults have?

Bilateral symmetry 

Ambulicrarian characteristics 

No head

Move equally well in all directions 

Mouth —> oral side (bottom) surface 

Anus —> aboral (top) surface 

What symmetry do adult echinoderms have?

Pentaradial symmetry

What do enchinoderms use water for?

Tube feet use it for hydraulic pressure (locomotion and adhesion)

What do sea urchins produce for defense?

Toxins

How are tube feet in sea cucumbers different?

They are used to anchor substrate instead of walking 

Sea cucumber body orientation

Mouth anterior and anus posterior

What are tube feet in sea stars used for?

Locomotion, gas exchange and attachment, capture large prey

Where are the gonads and digestive organs located in sea stars?

Arms

How do sea star larva move?

Via cilia 

What is a key feature shared by echinoderms and hemichordates?

Both have ciliated, bilaterally symmetrical larvae 

What is the function of the water vascular system in echinoderms?

Locomotion and adhesion through hydraulic pressure in tube feet

Hemichordate characteristics

Acorn worms and pterobranches

Hemichordates characteristics

Bilateral symmetry

3 part body plan- proboscis, collar, trunk

What kind of symmetry do hemichordates have?

Bilateral 

How do acorn worms capture prey?

Large proboscis covered in sticky mucus

Where do acorn worms live?

Burrow in soft marine sediments

Where to pterobranchs live?

Tubes secreted by proboscis

How do pterobranchs capture prey?

Tentacles 

What is the purpose of the collar in Pterobranchs?

Prey capture and gas exchange

Larval vs. adult sea star body plan

Larva- cilia /bilateral

Adult- tube feet/pentaradial

Hemichordate vs enchinoderm feeding difference

Hermichordates- large proboscis

Enchinoderms- tube feet

Derived characteristics of all chordates

Dorsal, hollow nerve cord

Tail extending beyond anus

Notochord

3 kinds of chordates 

Lancelets, tunicates,vertebrates 

Do tunicates have a notochord?

No it is lost

Do lancelets have a notochord?

Yes

Do vertebrates have a notochord?

No, replaced by vertebral column 

Why is notochord important?

Important in development of the nervous system and provides structural support

What do lancelets use to filter prey?

The pharynx becomes a pharyngeal basket

Where does fertilization take place in lancelets?

Water

What makes up the hagfishes 

Hagfish and lamprey

What kind of development do hagfish have?

Direct

Anadromous

Live in salt water but migrate to freshwater to breed

Adult lamprey feeding

Many are parasitic and others are nonfeeding

What animals are chondrichthyans?

Sharks, rays, skates, chimaeras 

How do sharks swim?

Lateral undulations of the body

How do skates and rays swim?

Flapping enlarged pectoral fins

Sharks vs. skates/rays swimming

Lateral undulations of the body vs. flapping enlarged pectoral fins

What do the gas filled sacs do in bony vertebrates?

Supplement gills in gas exchange 

What do sacs in ray finned fishes do?

Develop into swim bladders for buoyancy

Why is the operculum important in ray finned fishes?

Movement enhances water flow over the gills

Four chambered heart function

Completely separates oxygenated from deoxygenated blood

What are key features in mammals?

Sweat glands, mammary glands, hair, four chambered heart 

How are mammal eggs fertilized?

Internally

What is the purpose of a placenta

Nutrient and gas exchange

Waste elimination

How do cetaceans (whales and dolphins) insulate themselves?

Layers of fat replace hair for insulation

What are the two groups of living mammals?

Prototheirans and therians 

Therians

All other mammals

What are the two groups of Therians?

Marsupials and eutherians

Which is the only marsupial in North America?

Virginia opossum

Marsupial feeding 

Herbivores, insectivores, carnivores

Difference between young in marsupials vs eutherians

Young are more developed at birth

What did plants do to protect themselves after animals began eating them more?

Plant spines, making them harder to digest

What eutherian lineage returned to aquatic habitat?

Cetaceans (whales and dolphins)

What is a major adaptation that distinguishes primates?

Grasping limbs with opposable digits 

What are the two clades of primates?

Wet nosed and dry nosed

Wet nosed primates

Lemurs, lorises, and galagos

Dry nosed primates

Tarsiers, new world monkeys, old world monkeys, apes

New world monkeys vs old world

Arboreal w/prehensile tails vs arboreal + terrestrial w/no prehensile tails 

Which are the closest living sister group of modern African apes?

Orangutans

Advantages of bipedal locomotion

Energetically economical, forelimbs can manipulate + carry objects, elevates eyes to look for prey

What happened as brain sized increased in Homo Sapiens?

Brain size increased rapidly and jaw muscles decreased in size

Evolution by neoteny (humans)

Adult human skull stays about the same shape as baby skull and is large relative to other features 

What happens to skull size in chimpanzees as they mature?

Skull shape changes dramatically

Benefits of increasing brain size

Favored by increasingly complex social life bc increased communication

What is a commonality of the homo species

They all hunted large mammals

Where were Homo neanderthalensis found?

Europe and Asia 

Characteristics of Homo neanderthalensis

Short and stocky w/large brains

Do hagfishes have a strong circulatory system?

No

What became more muscular in lobe limb vertebrates?

Paired pelvis and pectoral fins

What is a dervied feature in coelocanths?

Cartilaginous skeleton

Why are lungs and gills important in lungfishes?

Burrow in mud when ponds dry up and survive many months in inactive state while breathing air 

How did aquatic lobe limbed vertebrates evolve to become ancestral tetrapods?

Began using terrestrial food sources

Where do amphibians live?

Most in moist habitats others in land

Why do adult amphibians return to water?

To lay eggs

Where does amphibian larvae develop?

Water

What are the three groups of amphibians?

Caecilians,anurans, tailed salamanders

What composes the anurans?

Tailless frogs and toads

Do caecilians have limbs?

No

How do anurans hop/leap or kick in the water?

Short vertebral column and pelvic region 

How does a group of salamanders have gas exchange if they have no lungs?

Skin and mouth lining

Complex social behaviors in amphibians

Anurans—> call to attract females + defend territories

Lay few eggs + guard nest

Carry eggs on body

What do features in amniotes allow them to do?

Conserve water and exploit terrestrial habitats 

Why is important that the shell in the amniote egg is leathery or brittle?

Retard water evaporization and allow for gas exchange

How do amniote eggs store food?

Yolk

Extraembryonic membranes

Protect embryo from drying

Assist in gas exchange and excretion of nitrogen

Kidney function

Retain water, excrete concentrated urine and nitrogen waste